1. Field of the Invention
The present invention refers to a chain-type flexible cutting edge, in particular for bush-cutters.
2. Background Art
As known, the bush-cutter is a tool used for cutting bushes, shrubs and grass in places not accessible with other machines. It is carried on straps or on the shoulders by an operator and is equipped with an engine of the electric or combustion type that, through a transmission shaft placed inside a rod, actuates, by rotating it, a rigid toothed disk or a mowing head that usually supports from two to four flexible cutters, made as nylon wires, thin metal cables or chains.
In the particular case of mowing heads, the chains used as flexible cutting edges usually are of three types:                chains with normal, ring-type links connected to the head at only one of their ends: such chains, given their shape, have a scarce flexibility, and therefore tend to brake when they encounter a particularly hard obstacle. When this occurs, the operator must stop his mowing work, disassemble the mowing head and replace the chain. Not rarely such inconvenience occurs rather frequently during the mowing work, and it is clear therefore that these continuous interruptions bring about unpleasant losses of time, in addition to an unavoidable frustration for the operator. Moreover, such chains are not suitable for cutting trees or plants with wooden stock with large diameters;        plane roller-type chains connected to the head at only one of their ends (like those described, for example, in U.S. Pat. No. 2,676,448 in the name of LIMBERGER Frank W., in FR-A-2 651 089 in the name of DECOSTANZI Arnold, and in U.S. Pat. No. 4,631,828 in the name of BURNET Robert J.: such chains have a higher flexibility than the previous ones, but they are also unsuitable for cutting trees and plants with wood stocks with large diameters; and        toothed roller-type chains connected to the head at both their ends in order to form a ring: such chains are adapted for cutting trees and plants with wood stocks with large diameters, but not grass and thinner shrubs, that instead of being cut, are torn. In such case, it is therefore necessary to exchange the mowing head with another one equipped with a different type of cutting edge. Moreover, it is their ring-type structure that also makes them scarcely flexible and therefore subjected to frequent breakages in case of impacts against hard obstacles.        